Online template attack (OTA) is a powerful technique previously used to attack elliptic curve scalar multiplication algorithms. This attack has been only analyzed in the realm of power-consumption and EM side-channels, where the signals leak about the value to be processed. However, no microarchitecture analysis variant has been proposed, especially considering the different nature between power-consumption signals and microarchitecture-based ones. 
In this paper we start filling this gap by revisiting the original OTA description, proposing a generic framework and evaluation metrics for any side-channel signal. Our analysis reveals OTA features not covered before, increasing its application scenarios that requires revisiting original countermeasures to prevent it. In this regard we demonstrate that OTA can work in the backward direction allowing to mount an augmented projective coordinates attack wrt the proposed by Naccache et al. (Eurocrypt 2004). 
We analyze three libraries libgcrypt, mbedTLS, and wolfSSL using two microarchitecture side-channels. For the libgcrypt case we target its EdDSA implementation using Curve25519 twist curve. We obtain similar results for mbedTLS and wolfSSL with curve secp256r1. For each library we execute extensive attack instances being able to recover the complete scalar in all cases using a single trace. 
In this work demonstrate that microarchitecture online template attacks are also very powerful in this scenario, recovering secret information without knowing a leakage model. This highlights the importance of developing secure-by-default implementations, instead of fix-on-demand ones.

Microarchitecture Online Template Attacks

Fault Diagnosis of Rotating Machinery Based on Dimensionless Index and Two-sample Distribution Test

An online template attack (OTA) is a powerful technique previously used to attack elliptic curve scalar multiplication algorithms. This attack has only been analyzed in the realm of power consumption and EM side channels, where the signals leak related to the value being processed. However, microarchitecture signals have no such feature, invalidating some assumptions from previous OTA works. 
In this paper, we revisit previous OTA descriptions, proposing a generic framework and evaluation metrics for any side-channel signal. Our analysis reveals OTA features not previously considered, increasing its application scenarios and requiring a fresh countermeasure analysis to prevent it. 
In this regard, we demonstrate that OTAs can work in the backward direction, allowing to mount an augmented projective coordinates attack with respect to the proposal by Naccache, Smart and Stern (Eurocrypt 2004). This demonstrates that randomizing the initial targeted algorithm state does not prevent the attack as believed in previous works. 
We analyze three libraries libgcrypt, mbedTLS, and wolfSSL using two microarchitecture side channels. For the libgcrypt case, we target its EdDSA implementation using Curve25519 twist curve. We obtain similar results for mbedTLS and wolfSSL with curve secp256r1. For each library, we execute extensive attack instances that are able to recover the complete scalar in all cases using a single trace. 
This work demonstrates that microarchitecture online template attacks are also very powerful in this scenario, recovering secret information without knowing a leakage model. This highlights the importance of developing secure-by-default implementations, instead of fix-on-demand ones.

/pdf/online-template-attacks-revisited-3jd805z1mz.pdf

Online Template Attacks: Revisited

Considering the former attack algorithm was impacted by noise easily, a trace driven data Cache timing attack model on RSA was built, and the analysis algorithm of the power exponent was provided based on the Cache hit or miss side channel information. This paper proposes a new algorithm for automated analysis of the abundant Cache timing data based on these, which combines the vector quantization and Hidden Markov Model (HMM) cryptanalysis. We built a template for Cache timing analysis, and get the operation sequence using the Viterbi algorithm with HMM, to improve the precise of analysis. Finally, under the practical environment, we realized a Cache timing attack on RSA of OpenSSL. The experiment results showed that: the proposed analysis algorithm can effectively reduce the influence of noises from other processes, make the analysis of Cache timing data automatically, and the effectiveness and feasibility of Cache timing attack on RSA also can be improved.

Yang-xia Xiang

Papers

An improved Data Cache Timing Attack against RSA Based on Hidden Markov Model

Improved Fault Analysis on RSA based on Non-invasive Fault